Method for producing porous carbon support and porous carbon support produced thereby

Abstract

The present invention can provide a method for producing a porous carbon support, including: (1) a step of synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) a step of solidifying and pelletizing the pitch to obtain solid pitch pellets; (3) a step of stabilizing the solid pitch pellets without crushing them; and (4) a step of carbonizing the stabilized pitch pellets to obtain a carbonized body.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a porous carbon support and a porous carbon support produced thereby. [Background technology]

[0002] Carbon materials are made from carbon, one of the most common resources on Earth. They are extremely light, strong, and have excellent electrical and thermal conductivity, making them a core material widely used in fields such as hydrogen vehicles, aviation, secondary batteries, and luxury consumer goods.

[0003] Carbon materials can be produced from various raw materials such as coconut shells, polyacrylonitrile, rayon, and pitch, but among them, carbon materials produced from solid raw materials such as coconut shells have difficulty in controlling their molecular weight and components (Korean Patent Publication No. 10-2019-0093960).

[0004] Meanwhile, pitch, a viscoelastic solid polymer extracted from crude oil or plants, has advantages over other raw materials in that it has a high yield when converted into carbon materials, is inexpensive, and has a molecular structure closer to that of graphite than other raw materials, reducing the energy required for heat treatment (U.S. Patent Nos. 4,242,196 and 4,340,464).

[0005] In particular, pyrolysis fuel oil (PFO), naphtha cracking bottom oil (NCB), vacuum residue (VR), and fluid catalytic cracking decant oil (FCC-DO), which are obtained as by-products in the petroleum refining process, have high aromatic compound contents and low impurity contents such as sulfur and nitrogen, and therefore the pitch produced from these products is attracting attention as a source of carbon materials.

[0006] Conventionally, porous carbon supports have been prepared by preparing pellet-shaped carbon precursors from such pitch, grinding them into powder, and then activating them. However, since the porous carbon supports prepared in this manner mainly contain micropores, there is a problem that deposition cannot be achieved well in deep pores when chemical vapor deposition (CVD) or the like is performed in a subsequent process. Summary of the Invention [Problem to be solved by the invention]

[0007] One of the various objects of the present invention is to provide a method for producing a porous carbon support having controlled pore characteristics and capable of being deposited sufficiently deep into pores during chemical vapor deposition, and a porous carbon support produced thereby.

[0008] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having a high charge / discharge capacity, and a porous carbon support produced thereby.

[0009] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having improved cycle characteristics, and a porous carbon support produced thereby.

[0010] One of the various objects of the present invention is to provide a method for producing a porous carbon support that can produce a negative electrode material having excellent mechanical properties, and a porous carbon support produced thereby. [Means for solving the problem]

[0011] According to one embodiment of the present invention, the present invention can provide a method for producing a porous carbon support, including: (1) synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) solidifying and pelletizing the pitch to obtain solid pitch pellets; (3) stabilizing the solid pitch pellets without crushing them; and (4) carbonizing the stabilized pitch pellets to obtain a carbonized body.

[0012] In this case, the polycondensation temperature of the pitch synthesis in step (1) may be in the range of 350°C or more and / or 500°C or less.

[0013] In addition, the softening point of the pitch synthesized in step (1) may be 200°C or higher.

[0014] In one embodiment of the present invention, the thickness of the solid pitch pellet in step (3) of the method for producing a porous carbon support according to the present invention may be 1 mm or more.

[0015] In one example, step (3) of the method for producing a porous carbon support according to the present invention includes a step of heating unground solid pitch pellets at a temperature of 250°C or higher and / or 400°C or lower, and the heating can be performed by microwave or plasma.

[0016] The oxygen content of the pitch pellets stabilized in the step (3) may be 10% by weight or more.

[0017] In addition, the distribution deviation of the oxygen content in the cross section of the pitch pellet stabilized in the step (3) may be 30% or less.

[0018] In one example, the method for producing a porous carbon support according to the present invention may further include a step of depositing silicon after step (4).

[0019] In this case, the deposition may be performed at a temperature of 300° C. or more and / or 600° C. or less under a silane (SiH 4 ) gas atmosphere of 50 sccm or more and / or 500 sccm or less.

[0020] The content of the deposited silicon may be 10 wt % or more based on the weight of the entire porous carbon support.

[0021] Another embodiment of the present invention may provide a porous carbon support prepared by the above-described method.

[0022] Another embodiment of the present invention may provide a battery anode material including the porous carbon support described above. [Effects of the Invention]

[0023] According to one of the various effects of the present invention, a method for producing a porous carbon support in which mesopores are formed in the outer periphery and micropores are formed in the deep portion, and silicon can be sufficiently deposited even in the deep pores, and a porous carbon support produced thereby can be provided.

[0024] According to one of the various effects of the present invention, it is possible to provide a method for producing a porous carbon support that can produce a negative electrode material having a high charge / discharge capacity, and a porous carbon support produced thereby.

[0025] According to one of the various effects of the present invention, it is possible to provide a method for producing a porous carbon support that can produce a negative electrode material having improved cycle characteristics, and a porous carbon support produced thereby.

[0026] According to one of the various effects of the present invention, it is possible to provide a method for producing a porous carbon support that can produce a negative electrode material having excellent mechanical properties, and a porous carbon support produced thereby.

[0027] However, the various beneficial advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is an SEM image of the cross section of the pitch in Production Example 1 immediately after stabilization. [Figure 2] FIG. 2 is an SEM image of the cross section of the pitch in Production Example 3 immediately after stabilization. [Figure 3]FIG. 3 is a graph showing the results of electrochemical evaluation of half coin cells fabricated using the porous carbon supports of Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described with reference to specific embodiments and the accompanying drawings. This is not intended to limit the technology described in this specification to the specific embodiments, but should be understood as including various modifications, equivalents, and / or alternatives of the embodiment examples of the present invention. In describing the drawings, similar reference numerals may be used for similar components.

[0030] In addition, in the drawings, in order to clearly explain the present invention, parts that are not relevant to the explanation are omitted, and thicknesses are exaggerated to clearly represent multiple layers and regions, and components that have the same function within the same conceptual scope may be described using the same reference symbols.

[0031] In this specification, the terms "have," "may have," "include," or "may include" refer to the presence of a given feature (e.g., a value, function, operation, or component such as a part) and do not exclude the presence of additional features.

[0032] As used herein, phrases such as "A or B," "at least one of A and / or B," and "one or more of A and / or B" may include all possible combinations of the listed items. For example, "A or B," "at least one of A and B," or "at least one of A or B" can refer to all of the following: (1) including at least one A; (2) including at least one B; or (3) including both at least one A and at least one B.

[0033] All numbers and expressions expressing quantities of components, reaction conditions, and the like described herein, unless otherwise specified, are understood to be modified in all instances by the term "about." should be.

[0034] The present invention relates to a method for producing a porous carbon support. The method for producing a porous carbon support according to one embodiment of the present invention may include: (1) synthesizing pitch by pyrolysis and polycondensation of a petroleum-based raw material; (2) solidifying and pelletizing the pitch to obtain solid pitch pellets; (3) stabilizing the solid pitch pellets without crushing them; and (4) carbonizing the stabilized pitch pellets to obtain a carbonized body.

[0035] Each step of the present invention will now be described in detail.

[0036] In the method for producing a porous carbon support according to the present invention, step (1) may be a step of synthesizing pitch by pyrolysis and polycondensation of a petroleum-based raw material.

[0037] In an embodiment of the present invention, the petroleum-based feedstock may comprise at least one selected from the group consisting of thermal cracking fuel oil (PFO), naphtha cracked bottom oil (NCB), ethylene cracker bottom oil (EBO), vacuum residue (VR), deasphalted oil (DAO), atmospheric residue (AR), fluid catalytic cracking decant oil (RFCC-DO), residue fluid catalytic cracking decant oil (RFCC-DO), and heavy aromatic oil. In a preferred embodiment of the present invention, the petroleum-based feedstock may comprise thermal cracking fuel oil.

[0038] In a specific example of the present invention, the pyrolysis and polycondensation of the petroleum-based feedstock may be carried out at a temperature of 350°C or higher and / or 500°C or lower. The pyrolysis and polycondensation temperature may be 350°C or higher, 360°C or higher, 370°C or higher, 380°C or higher, 390°C or higher, 400°C or higher, 410°C or higher, 420°C or higher, or 430°C or higher, and may be 500°C or lower, 490°C or lower, 480°C or lower, or 470°C or lower, but is not limited thereto. When the pyrolysis and polycondensation temperatures are within the above ranges, a pitch containing a large amount of relatively low molecular weight components can be produced. Furthermore, during the activation process described below, the relatively low molecular weight components are vaporized first, thereby allowing sufficient formation of mesopores in the carbon support. If the pyrolysis and polycondensation temperatures of the petroleum-based feedstock are too low, it may be difficult to produce a solid pitch at room temperature. If the temperatures are too high, the pitch may contain a large amount of relatively high molecular weight components, making it impossible to produce a carbon support with mesopores.

[0039] In an embodiment of the present invention, the pyrolysis and polycondensation of the petroleum-based feedstock may be carried out in an atmosphere of an oxidizing gas, an inert gas, or a mixture thereof. In a preferred embodiment of the present invention, the oxidizing gas may be oxygen, ozone, or a combination thereof, the inert gas may be nitrogen, helium, neon, argon, or a combination thereof, and the mixture may be air, but is not limited thereto.

[0040] When an oxidizing gas is used during the thermal decomposition and condensation polymerization of petroleum-based raw materials, pitch with a high softening point can be produced, but it is difficult to carry out the thermal decomposition and condensation polymerization at high temperatures. When an inert gas is used during the thermal decomposition and condensation polymerization of petroleum-based raw materials, pyrolysis and condensation polymerization can be carried out at high temperatures, but it is difficult to produce pitch with a relatively high softening point. When a mixed gas of an oxidizing gas and an inert gas is used during the thermal decomposition and condensation polymerization of petroleum-based raw materials, pyrolysis and condensation polymerization can be carried out at a relatively high temperature, so pitch with a relatively high softening point can be produced.

[0041] In a specific example of the present invention, the above gas may be supplied at a flow rate of 10 to 800 ml / min during the thermal decomposition and polycondensation of the petroleum-based raw material. During the pyrolysis and polycondensation, the gas may be supplied at a flow rate of 100 to 500 ml / min. If the flow rate of the gas is less than 10 ml / min, the pitch yield will be high, but the amount of low-molecular-weight components will be too high, which is disadvantageous for subsequent processes (e.g., stabilization). If the flow rate of the gas is more than 800 ml / min, the pitch yield may be low.

[0042] In an embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 1 to 10 hours. In a preferred embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 2 to 8 hours. In a more preferred embodiment of the present invention, the pyrolysis and condensation polymerization of the petroleum-based feedstock may be carried out for 2 to 7 hours. If the pyrolysis and condensation polymerization time of the petroleum-based feedstock is less than 1 hour, it is difficult to produce a pitch with a high softening point, and if the pyrolysis and condensation polymerization time of the petroleum-based feedstock exceeds 10 hours, an excessive amount of quinoline-insoluble components may be produced.

[0043] In a specific example of the present invention, the pyrolysis and polycondensation of the petroleum-based raw material may be carried out under stirring. The stirring conditions for the petroleum-based raw material are not particularly limited, but for example, a stirrer rotating at 10 to 500 rpm may be used.

[0044] In an embodiment of the present invention, the softening point of the pitch synthesized in step (1) may be 200°C or higher. Because the pitch synthesized in step (1) has a high softening point, when used as a precursor for preparing a carbon support, the stabilization process is easy and a high yield can be obtained after carbonization and activation. The upper limit of the softening point of the pitch may be, for example, but is not limited to, 350°C or lower, 330°C or lower, or 300°C or lower.

[0045] In an embodiment of the present invention, the yield of pitch synthesized in step (1) may be 10-50 wt%. In another embodiment of the present invention, the yield of pitch may be 10-40 wt%. In yet another embodiment of the present invention, the yield of pitch may be 20-30 wt%.

[0046] In the process for preparing a porous carbon support from a petroleum-based feedstock according to an embodiment of the present invention, a pretreatment step of the petroleum-based feedstock may be performed prior to step (1). By removing low-boiling point components contained in the petroleum-based feedstock through the pretreatment step, a pitch with a higher softening point can be produced.

[0047] In an embodiment of the present invention, the pretreatment step may be carried out at a temperature equal to or lower than the temperature of the pyrolysis and polycondensation of the petroleum-based feedstock in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be carried out at a temperature of 250 to 450°C, preferably 250 to 400°C, and more preferably 300 to 400°C.

[0048] In an embodiment of the present invention, the pretreatment step may be carried out for a time equal to or shorter than the time for pyrolysis and polycondensation of the petroleum-based feedstock in step (1), but is not particularly limited to this condition. Specifically, the pretreatment step may be carried out for 1 to 8 hours, preferably 1 to 6 hours, and more preferably 1 to 5 hours.

[0049] Stage 2

[0050] In the method for producing a porous carbon support according to the present invention, step (2) may be a step of solidifying and pelletizing pitch to obtain solid pitch pellets.

[0051] The liquid pitch obtained in step (1) is solidified, for example, by extrusion and cooling, and then pelletized to a desired size to obtain solid pitch pellets. The process of pelletizing the pulp to obtain solid pitch pellets can be carried out using commercially available equipment, for example, but not limited to, an IPCO Double Belt Cooler & Flaker.

[0052] The pitch pellets obtained in step (2) have an average particle size of 3 to 30 mm, preferably 5 to 25 mm. When the average particle size of the pitch pellets is within this range, the pitch pellets can be stabilized, carbonized, and activated as described below to produce a porous carbon support without being crushed separately. This allows for a simple process to improve product yield and provide a porous carbon support with controlled pore characteristics.

[0053] Stage 3

[0054] In the method for producing a porous carbon support according to the present invention, step (3) may be a step of stabilizing solid pitch pellets without crushing them. Specifically, it may be a step of primarily oxidizing uncrushed solid pitch pellets to stabilize the pitch structure.

[0055] The method for producing a porous carbon support according to the present invention does not require pulverizing the solid pitch pellets produced in step (2). Conventionally, a porous carbon support has been produced by preparing a carbon precursor in the form of pellets, pulverizing them into powder, and then performing an activation process. This is because, if the pellets are stabilized in an unpulverized state, oxygen cannot penetrate the pellets, preventing reaction with oxygen. Therefore, the isotropy of the pitch cannot be maintained during the carbonization and activation processes, and the interior of the pellets becomes coked during carbonization, preventing smooth development of pores. However, pulverizing the produced pellets has drawbacks, such as a somewhat complicated process and a reduced yield during the pulverization process. The method for producing a porous carbon support according to the present invention simplifies the process and improves process efficiency by stabilizing the solid pitch pellets produced in step (2) without pulverizing them.

[0056] In one embodiment of the present invention, the thickness of the solid pitch pellets stabilized in step (3) may be 1 mm or more. The thickness of the pitch pellets may refer to, for example, the shortest length of an imaginary line passing through the center of the pitch pellets. The thickness of the solid pitch pellets may be 1 mm or more, 2 mm or more, or 3 mm or more, and may be 10 mm or less, 9 mm or less, or 8 mm or less, but is not limited thereto. If the solid pitch pellets stabilized in step (3) are not pulverized, they can meet the above thickness. By undergoing the stabilization step described below, a porous carbon support having excellent pore characteristics and that can be effectively used in various applications can be produced.

[0057] In one embodiment of the present invention, the stabilization of pitch pellets may be performed at a temperature of 250°C or higher and / or 400°C or lower. The stabilization temperature of the pitch pellets may be 250°C or higher, 260°C or higher, 270°C or higher, or 280°C or higher, and may be 400°C or lower, 390°C or lower, 380°C or lower, 370°C or lower, 360°C or lower, or 350°C or lower, but is not limited thereto. When the stabilization temperature of the pitch pellets satisfies the above range, the carbon structure within the pitch changes from thermoplastic to thermosetting, and the structure can then be stably maintained during the carbonization process.

[0058] In this case, the temperature rise rate may be 0.5°C / min or more and / or 10°C / min or less. The temperature rise rate may be 0.5°C / min or more, 1°C / min or more, or 2°C / min or more, and may be 10°C / min or less, 8°C / min or less, or 6°C / min or less, but is not limited to these. If the temperature rise rate is too slow, the pellet may not be sufficiently stabilized to the inside. Also, if the temperature rise rate is too fast, the reaction time with oxygen may be shortened, the temperature may rise too quickly, and the pitch may melt without cross-linking.

[0059] In one example, the heating can be performed using microwaves and / or plasma. In conventional methods for producing porous carbon supports, pellets are heated by various methods in the stabilization step. Typical heating methods for the stabilization step include heating using an electric furnace, but these methods can result in insufficient heat transfer in the thickness direction, making it difficult to achieve uniform heat treatment. This can lead to problems such as pitch melting without stabilization, inability to develop pores during the carbonization and activation processes, or insufficient structural stabilization of the pitch. Therefore, in conventional production methods, solid pitch pellets are crushed to form powder and then stabilized. In contrast, in the method for producing a porous carbon support according to the present invention, the pitch pellets are heated using microwaves and / or plasma, which allows the pitch pellets to be heated from the inside of the pitch, thereby enabling uniform heating. This promotes oxygen diffusion into the interior, making it possible to produce a porous carbon support with excellent pore characteristics even when uncrushed pitch pellets are immediately stabilized without crushing.

[0060] In an embodiment of the present invention, the stabilization of the pitch pellets can be carried out at a pressure of 0.1 to 10 bar, preferably 0.5 to 5 bar. When the stabilization of the pitch pellets is carried out at this pressure, the structure of the carbon inside the pellets can be sufficiently stabilized.

[0061] In a specific example of the present invention, the stabilization of pitch pellets can be carried out under the condition of an oxidizing gas, preferably air or oxygen, flowing at a rate of 0.1 to 500 ml / min, preferably 1 to 300 ml / min. When the stabilization of pitch pellets is carried out under this oxidizing gas flow rate, the structure of the carbon inside the pellets can be sufficiently stabilized.

[0062] In an embodiment of the present invention, the stabilization of the pitch pellets can be carried out for 1 to 10 hours, preferably 2 to 8 hours. When the stabilization of the pitch pellets is carried out within this time, the structure of the carbon inside the pellets can be sufficiently stabilized.

[0063] In one example, the oxygen content of the stabilized pitch pellets in step (3) of the method for producing a porous carbon support according to the present invention may be 10 wt% or more based on the weight of the total pitch pellets. The oxygen content of the stabilized pitch pellets may be a value measured using SEM-EDS. The oxygen content of the pitch pellets may be 10 wt% or more, 12 wt% or more, 14 wt% or more, or 15 wt% or more based on the weight of the total pitch pellets, but is not limited to these.

[0064] The pitch pellets may be stabilized by heating with microwaves and / or plasma. When the pitch pellets are heated with microwaves and / or plasma, uniform heat treatment can be achieved by heating from the inside of the pellets, thereby allowing the oxygen content of the stabilized pitch pellets to satisfy the above range. If the oxygen content of the stabilized pitch pellets is too low, there may be insufficient oxygen to act as a cross-link during the carbonization process, which may lead to melting or coking. Furthermore, if the oxygen content of the stabilized pitch pellets is too high, excessive reaction with oxygen may occur, resulting in a reduced yield during the carbonization process and impeded structural development.

[0065] In another example, the pitch pellet stabilized in step (3) of the method for producing a porous carbon support according to the present invention may have a distribution deviation of oxygen content in a cross section of 30% or less. The oxygen content in the cross section of the stabilized pitch pellet may be a value measured using line profiling using SEM-EDS, and the distribution deviation d of the oxygen content may be calculated by calculating the average M of the oxygen content (wt%) measured in the cross section of the sample and then calculating the largest difference from the average. The deviation of the oxygen content distribution in the cross section of the pitch pellet stabilized in step (3) may be 30% or less, 28% or less, 26% or less, 24% or less, 22% or less, or 20% or less, and the lower limit is not particularly limited, and may be, for example, 0% or more, more than 0%, 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more, but is not limited thereto.

[0066] As described above, the pitch pellets in step (3) of the method for producing a porous carbon support according to the present invention may be stabilized by heating them in an unground state using microwaves and / or plasma. When unground pitch pellets are heated in air using a general electric furnace, the difference in heating rate between the center and periphery of the pitch pellets may result in a large deviation in the distribution of oxygen content. On the other hand, in the method for producing a porous carbon support according to the present invention, the unground pitch pellets are stabilized using microwaves and / or plasma, which allows for uniform heat treatment and a low deviation in the oxygen content. If the deviation in the distribution of oxygen content in the cross section of the stabilized pitch pellets in step (3) is too high, the pellet structure and the pore structure formed therefrom may develop unevenly due to the non-uniformity of the oxygen content.

[0067] The method of heating the unground pitch pellets in step (3) with microwaves and / or plasma is not particularly limited as long as it can sufficiently heat the pitch pellets. For example, the pitch pellets can be heated with microwaves at an output of 500 W to 1000 W, but is not limited thereto. Furthermore, the heating can be performed using DC or RF plasma under vacuum (500 mTorr or less) or atmospheric pressure, but is not limited thereto.

[0068] Stage (4)

[0069] In the method for producing a porous carbon support according to the present invention, step (4) may be a step of carbonizing the stabilized pitch pellets to obtain a carbonized body. Through the carbonization of the pitch pellets, other functional groups contained in the pitch are removed, thereby obtaining a carbonized body consisting of substantially pure carbon.

[0070] In an embodiment of the present invention, the carbonization of the pitch can be carried out under an inert gas atmosphere. In a preferred embodiment of the present invention, the carbonization of the pitch is carried out under a nitrogen or argon atmosphere, but is not particularly limited thereto.

[0071] In an embodiment of the present invention, the carbonization of the pitch may be carried out at a temperature of more than 700° C. and not more than 1,000° C., preferably 800 to 900° C. If the temperature during the carbonization of the pitch is lower than this range, the carbonization may not be sufficient, and if the temperature during the carbonization of the pitch is higher than this range, the carbonization yield may decrease.

[0072] In a specific example of the present invention, the carbonization of the pitch can be carried out under the condition of an inert gas, preferably nitrogen, flowing at a rate of 0.1 to 30 ml / min, preferably 0.1 to 10 ml / min. When the carbonization of the pitch is carried out under this inert gas flow rate condition, the pitch can be sufficiently carbonized.

[0073] In an embodiment of the present invention, the carbonization of the pitch can be carried out for 0.5 to 5 hours, preferably 1 to 3 hours. When the carbonization of the pitch is carried out within this time, the pitch can be sufficiently carbonized.

[0074] Stage (5)

[0075] In the method for producing a porous carbon support according to the present invention, a porous carbon support can be obtained by activating a carbonized body in step (5). Pores are formed in the pitch through activation of the carbonized body (carbonized pitch), thereby obtaining a porous carbon support.

[0076] In an embodiment of the present invention, activation of the carbonized body may be carried out in an oxidizing gas atmosphere. In a preferred embodiment of the present invention, activation of the carbonized body may be carried out in a water vapor atmosphere, but is not particularly limited thereto.

[0077] In an embodiment of the present invention, the activation of the carbonized body can be carried out at a temperature of more than 700° C. and not more than 1,000° C., preferably 800 to 900° C. When the activation of the carbonized body is carried out at this temperature, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0078] In an embodiment of the present invention, the activation of the carbonized body can be carried out at a pressure of 0.1 to 10 bar, preferably 0.1 to 5 bar. When the activation of the carbonized body is carried out at this pressure, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0079] In an embodiment of the present invention, the activation of the carbonized body can be carried out under conditions of an oxidizing gas, preferably steam, flowing at a rate of 0.1 to 100 ml / min, preferably 0.1 to 50 ml / min. When the activation of the carbonized body is carried out under these oxidizing gas flow conditions, a porous carbon support having sufficiently formed micropores and mesopores can be obtained.

[0080] In an embodiment of the present invention, the activation of the carbonized body can be carried out for 0.5 to 5 hours, preferably 1 to 3 hours. When the activation of the carbonized body is carried out within this time, a porous carbon support with sufficiently formed micropores and mesopores can be obtained.

[0081] In an embodiment of the present invention, the above steps (4) and (5) can be carried out in a microwave and / or plasma furnace, respectively. In a preferred embodiment of the present invention, the above steps (4) and (5) can all be carried out in a microwave and / or plasma furnace. The microwave and / or plasma furnace can increase the temperature of the pitch pellets themselves without increasing the temperature of other parts of the furnace.

[0082] In an embodiment of the present invention, the above steps (3) to (5) can be continuously carried out in one apparatus. In a preferred embodiment of the present invention, the above steps (3) to (5) can be continuously carried out in one rotary kiln, but the present invention is not particularly limited to this apparatus. By continuously carrying out the stabilization, carbonization, and activation of pitch pellets in one apparatus, process optimization can be easily achieved.

[0083] In an embodiment of the present invention, the porous carbon support obtained in step (5) may be further crushed or pulverized and classified. The porous carbon support can be further pulverized through crushing or pulverization, and the particle size distribution of the porous carbon support can be made uniform through classification. Here, classification can be performed using dry classification, wet classification, or classification using a sieve. The crushing or pulverization and classification process can produce a porous carbon support powder with an average diameter of 1 to 20 μm.

[0084] In one embodiment of the present invention, the method for manufacturing a porous carbon substrate according to the present invention may further include a step of depositing silicon on the manufactured porous carbon substrate.

[0085] In this case, the deposition may be performed at a temperature of 300°C or higher and / or 600°C or lower in an atmosphere of silane (SiH4) gas at a flow rate of 150 sccm or higher and / or 500 sccm or lower. The deposition may be performed, for example, by chemical vapor deposition (CVD) under atmospheric pressure conditions, but is not limited thereto. Through the deposition, silicon may be deposited on the surface and inside the pores of the porous carbon support according to the present invention.

[0086] The present invention also relates to a porous carbon support. The porous carbon support according to the present invention may be prepared by the above-described method.

[0087] In one embodiment of the present invention, the porous carbon support according to the present invention may have a ratio of mesopore volume to total pore volume of 0.1 or more. The pores of a porous carbon support can be classified into micropores with a diameter of less than 2 nm, mesopores with a diameter of 2 to 50 nm, and macropores with a diameter of more than 50 nm, depending on their size. Research on such porous supports has focused on increasing the proportion of micropores to increase the specific surface area, or increasing the proportion of macropores to increase the amount of material supported inside the pores. However, when there are many micropores, silicon deposition inside the pores is difficult, resulting in a problem of reduced electrical capacity. Furthermore, when there are many macropores, silicon aggregates, generating stress during repeated charge / discharge processes, which can mechanically damage the negative electrode material.

[0088] On the other hand, in the case of mesopores, silicon can be sufficiently deposited deep within the pores during deposition. The porous carbon support according to the present invention has mesopores within a predetermined range, allowing a sufficient amount of silicon to be deposited inside the pores of the porous support.

[0089] The ratio of the volume of mesopores to the volume of total pores of the porous carbon support may be, but is not limited to, 0.10 or more, 0.12 or more, 0.14 or more, or 0.15 or more. The upper limit of the ratio of mesopores to total pores of the porous carbon support is not particularly limited, but may be, for example, 1.0 or less or less than 1.0. When the ratio of mesopores to total pores of the porous carbon support satisfies the above range, excessive silicon aggregation and damage due to volume expansion of silicon can be prevented while maintaining excellent electrical properties.

[0090] In one embodiment of the present invention, the tap density of the porous carbon support according to the present invention may be 0.7 g / ml or less. The tap density of the porous carbon support may be measured using a PT-TD200 (Pharma Test). Specifically, 40 ml of the porous carbon support is placed in a cylinder, tapped 1,000 times, and then the initial volume is observed. After the observation, the cylinder is tapped again 1,000 times and the volume is observed. This process is repeated three times until there is no difference from the previous volume, and the tap density can be calculated as the final volume. The tap density of the porous carbon support may be 0.70 g / ml or less, 0.65 g / ml or less, 0.60 g / ml or less, 0.55 g / ml or less, 0.05 g / ml or more, or 0.1 g / ml or more, but is not limited thereto. If the tap density of the porous carbon support is too low, process control during silane gas deposition may be difficult, resulting in reduced yield. Furthermore, if the tap density of the porous carbon support is too high, it may be difficult to achieve a uniform coating during vapor deposition of silane gas.

[0091] In one embodiment of the present invention, the BET specific surface area of ​​the porous carbon support according to the present invention is 300 m 2 / g or higher and / or 3000m 2 The BET specific surface area of ​​the porous carbon support may be in the range of / g. The BET specific surface area may be a value measured using an ASAP 2420 (Micromeritics Instrument (USA)). Specifically, the analysis is performed after vacuum drying at 300°C for 5 hours, and the specific surface area is measured by N2 / 77K Isothermal Analysis according to ISO9277. The BET specific surface area of ​​the porous carbon support can be calculated using the BET equation and the BJH equation from the adsorption (isothermal adsorption) results. 2 / g or more, 400m 2 / g or more or 500m 2 / g or more, and 2 / g or less, 2800m 2 / g or less, 2600m 2 / g or less or 2000m 2 / g or less, but is not limited thereto. If the BET specific surface area of ​​the porous carbon support is too low, the proportion of macropores may be high, which may reduce the mechanical strength of the anode material and may result in insufficient effective pores. Also, if the BET specific surface area of ​​the porous carbon support is too high, the proportion of micropores may be high, which may result in insufficient silicon deposition deep into the porous carbon support.

[0092] In one embodiment of the present invention, the diameter of the porous carbon support according to the present invention may be 20 μm or less. This diameter may refer to the D50 diameter, measured using a MICROTRAC S3500 instrument. Specifically, it may refer to the average value obtained by dispersing the porous carbon support in ethanol and then performing particle size analysis three times. The diameter of the porous carbon support may be 20 μm or less, 18 μm or less, 16 μm or less, 14 μm or less, or 12 μm or less, or 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more, but is not limited thereto. If the diameter of the porous carbon support is too small, silicon may be quickly filled into the interior during coating, and further coating may be performed on the surface, resulting in a thicker surface coating layer. In this case, deterioration during charge and discharge may be accelerated, and materials with small particle sizes may aggregate during electrode fabrication, resulting in significant deterioration of the aggregates. In addition, if the diameter of the porous carbon support is too large, it may be difficult to form a uniform silicon coating layer inside the support due to the difficulty in diffusing silane gas into the porous carbon support, and if the diameter of the porous carbon support is too large, it may be difficult to uniformly coat the current collector with slurry during electrode fabrication, resulting in reduced capacity uniformity.

[0093] In one example, the porous carbon support according to the present invention may include macropores with a diameter of more than 50 nm. In this case, the ratio of the volume of the macropores to the volume of all pores of the porous carbon support may be 0.4 or less. The ratio of the volume of the macropores to the volume of all pores of the porous carbon support may be, but is not limited to, 0.40 or less, 0.38 or less, 0.36 or less, 0.34 or less, 0.32 or less, or 0.30 or less. The lower limit of the ratio of the volume of the macropores to the volume of all pores of the porous carbon support is not particularly limited, but may be, for example, 0 or more or greater than 0. If the ratio of macropores in the porous carbon support is too high, the mechanical strength of the anode material manufactured using the porous carbon support may be reduced. Furthermore, localized aggregation of silicon may occur within the anode material, generating stress due to volume expansion during repeated charge and discharge, which may cause damage to the anode material.

[0094] In one example, silicon may be disposed on the surface and inside the pores of the porous carbon support according to the present invention. The silicon may be formed by vapor deposition, as described above. Because the porous carbon support according to the present invention has this structure, the negative electrode material prepared using the porous carbon support according to the present invention can have high electric capacity while minimizing the influence of volume expansion of silicon.

[0095] In another example, the content of the deposited silicon may be 10 wt % or more based on the weight of the total particles. The silicon content may be a value obtained by analysis using an energy dispersive spectrometer (EDS). The content of the deposited silicon may be, but is not limited to, 10 wt % or more, 15 wt % or more, 20 wt % or more, 25 wt % or more, or 30 wt % or more. Furthermore, the content of the deposited silicon may be 60 wt % or less, 58 wt % or less, 56 wt % or less, 54 wt % or less, 52 wt % or less, or 50 wt % or less. However, if the content of deposited silicon is too low, the electrical capacity may decrease. Also, if the content of silicon is too high, the problem caused by the volume expansion of silicon during charging and discharging cannot be solved, which may cause structural damage to the negative electrode material and reduce cycle characteristics.

[0096] The present invention also relates to a battery anode material comprising the porous carbon support described above. The battery anode material comprising the porous carbon support according to the present invention can have improved mechanical strength as well as high electrical capacity and excellent cycle characteristics.

[0097] The method for manufacturing the battery anode material is not particularly limited, and a general method for manufacturing a battery anode material can be used. For example, the battery anode material can be manufactured by mixing a porous carbon support, an active material, a conductive agent, a binder, etc., and coating / drying / rolling the mixture onto a member such as an electrode current collector, but is not limited thereto.

[0098] The present invention also relates to a battery comprising the aforementioned battery anode material. The battery comprising the battery anode material according to the present invention may be, but is not limited to, a lithium ion battery or an all-solid-state battery.

[0099] The lithium-ion battery may specifically include a positive electrode, a negative electrode, a separator, and an electrolyte. In this case, the negative electrode may include the battery negative electrode material described above. The positive electrode may be made of a material usable in lithium-ion batteries, such as, but not limited to, one or more positive electrode active materials selected from doped or undoped lithium nickel oxide, lithium cobalt oxide, lithium cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium nickel cobalt aluminum oxide, and a positive electrode current collector selected from aluminum, stainless steel, nickel, titanium, platinum, or alloys thereof. The separator may be a conventional separator usable in lithium-ion batteries. The separator may include, but is not limited to, one or more materials selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE).

[0100] The negative electrode of the lithium ion battery may include the above-described battery negative electrode material. The negative electrode may include a negative electrode current collector and a battery negative electrode material, and the negative electrode current collector may include one or more selected from, but not limited to, aluminum, stainless steel, nickel, titanium, platinum, or alloys thereof.

[0101] The electrolyte of the lithium ion battery may include, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a polymer electrolyte, or a molten inorganic electrolyte that can be used in a lithium ion battery.

[0102] The all-solid-state battery may specifically include, but is not limited to, a positive electrode, a negative electrode, and a solid electrolyte, and may further include a separator as needed. The positive electrode may include the above-described positive electrode active material, and may optionally include a positive electrode current collector as needed, but is not limited to these.

[0103] The negative electrode may include the battery negative electrode material according to the present invention. The negative electrode may have a single-layer structure including the battery negative electrode material, or may further include a negative electrode current collector as needed, but is not limited thereto.

[0104] The solid electrolyte can be selectively selected from those usable in all-solid-state batteries. The solid electrolyte may be, for example, one or more selected from the group consisting of garnet-type, Nasicon-type, LISICON-type, perovskite-type, and LiPON-type, but is not limited thereto. [Example]

[0105] Preferred examples are shown below to aid in understanding the present invention. However, the following examples are provided merely to facilitate understanding of the present invention, and the contents of the present invention are not limited to these examples.

[0106] Preparation Example 1: Preparation of porous carbon support

[0107] 300 g of petroleum residual oil (YNCC, HTC PFO (pyrolysis fuel oil)) was placed in a reactor equipped with a stirrer, and pyrolysis and polycondensation were carried out at 450°C for 3 hours while supplying nitrogen at a flow rate of 100 ml / min. During this time, the stirrer was rotated at a speed of 200 rpm to mix the reactants. The polymerized pitch was solidified and pelletized, yielding solid pitch pellets 3.0 mm thick.

[0108] The solid pitch pellets obtained above were placed in a rotary kiln and subjected to a stabilization process using 200W plasma, followed by stabilization, carbonization, and activation. The conditions for stabilization, carbonization, and activation are shown in Table 1 below.

[0109] The activated carbonized body was pulverized using a pulverizer (Netsch air jet mill) to prepare a porous carbon support.

[0110] [Table 1]

[0111] Manufacturing Example 2

[0112] A porous carbon support was prepared in the same manner as in Preparation Example 1, except that the thickness of the solid pitch pellet was changed as shown in Table 2 below and heating was performed using a microwave with an output of 800 W instead of plasma in the stabilization step.

[0113] Manufacturing Example 3

[0114] A porous carbon support was prepared in the same manner as in Preparation Example 1, except that the thickness of the solid pitch pellets was changed as shown in Table 2 below and heating was performed using a general electric furnace instead of plasma in the stabilization step.

[0115] Production Example 4

[0116] The prepared solid pitch pellets were pulverized to prepare a powder having a thickness of 200 μm, and then heated in a general electric furnace instead of plasma in the stabilization step. A porous carbon support was prepared in the same manner as in Preparation Example 1.

[0117] [Table 2]

[0118] Table 3 below shows the physical properties of the prepared porous carbon substrate. The specific surface area of ​​the porous carbon substrate was measured using a Belsorp Mini II in accordance with ASTM D4820-93. The tap density of the carbon substrate was measured using a tap density tester (Electrolab, ETD-1020x) in accordance with ASTM B527. The average particle size of the carbon substrate was measured using a particle size analyzer (Horiba, Laser Particle Analyzer, LA-960V2) in accordance with ASTM E112. The oxygen content and internal variation were measured by line profiling using SEM-EDS on the cross section of the pitch immediately after stabilization.

[0119] [Table 3]

[0120] FIG. 1 is an SEM image of the cross section of the pitch immediately after stabilization in Preparation Example 1, and FIG. 2 is an SEM image of the cross section of the pitch immediately after stabilization in Preparation Example 3. As shown in FIGS. 1 and 2, the oxygen content was measured by line profiling along a line passing through the center of the cross section of the pitch. In Table 3, the maximum deviation a of the oxygen content is the oxygen content value that is most different from the average oxygen content M. For example, in Preparation Example 1, the oxygen content in the cross section of the porous carbon support was in the range of 17.3±2.5, i.e., 14.8 to 19.8. In this case, the distribution deviation of the oxygen content may be in the range of (|(14.8-17.3)| / 17.3) percentage.

[0121] Example 1: Preparation of carbon-silicon composite particles

[0122] Carbon-silicon composite particles were produced using the porous carbon support produced in Production Example 1. 15 to 20 g of the porous carbon support powder from Production Example 1 was placed in a rotary kiln, and silane (SiH4) gas was injected to coat the porous carbon support.

[0123] Silane gas coating was performed at atmospheric pressure, at a temperature of 475° C., and at a flow rate of 300 sccm for 1 hour.

[0124] Example 2

[0125] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 2 was used.

[0126] Comparative Example 1

[0127] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 3 was used.

[0128] Comparative Example 1

[0129] Carbon-silicon composite particles were prepared in the same manner as in Example 1, except that the porous carbon support prepared in Preparation Example 4 was used.

[0130] [Table 4]

[0131] Table 4 shows the physical properties measured after silicon was deposited on the porous carbon support in Examples 1 and 2 and Comparative Example 1. In Comparative Example 1, the specific surface area was very low, and few pores were formed facing inward, so silicon could not be coated inside the pores. Referring to Table 4, it can be seen that the silicon content in Examples 1 and 2 and Comparative Example 1 all exceeded 30 wt%. From the above results, it can be seen that the method for producing a porous carbon support according to the present invention allows composite particles with a sufficient amount of silicon deposited thereon to be produced without pulverizing solid pitch pellets.

[0132] Experimental example: Electrochemical evaluation of secondary batteries

[0133] The produced carbon-silicon composite particles were used to fabricate half-coin cells.

[0134] The carbon-silicon composite particles of the examples and comparative examples, the conductive material, and the binder were mixed in a ratio of 8:1:1 to prepare a slurry. In this case, the conductive material was Super-P, and the binder was styrene butadiene rubber. The material used was a mixture of styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) in a weight ratio of 5:5.

[0135] The slurry was uniformly coated on copper foil and dried for about 1 hour in an oven at 80° C. After the primary drying, the coated foil was roll-pressed and dried for about 6 hours and 30 minutes in a vacuum oven at 120° C. to prepare a negative electrode plate.

[0136] A half coin cell was fabricated using the prepared negative electrode plate and lithium foil as a counter electrode. A porous polyethylene film was used as a separator, and a CR2032 half coin cell was fabricated under the conditions shown in Table 5 below.

[0137] The electrolyte was prepared by dissolving 1.3 M LiPF in a 3:5:2 volumetric mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). The electrolyte was prepared by dissolving 10 wt% fluoroethylene carbonate (FEC), 0.2 wt% lithium tetrafluoroborate (LiBF), 0.5 wt% vinylene carbonate (VC), and 1 wt% propane sultone (PS) as additives.

[0138] [Table 5]

[0139] In Table 5, AM, CM, and BM represent the active material (silane-deposited porous carbon support), conductor (Super P carbon black), and binder (styrene butadiene rubber / carboxymethyl cellulose 5:5), respectively, and EC, EMC, DMC, FEC, VC, and PS represent ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, fluoroethylene carbonate, vinylene carbonate, and propane sultone, respectively. Electrochemical analysis of the fabricated half-coin cells was performed under the following conditions.

[0140] Cutoff voltage (V): 0.005~1.5V (formation), 0.005~1.2V (cycle)

[0141] Formation C rate (C): 0.1C lithiation, 0.1C delithiation

[0142] Cycle C rate (C): 0.5C lithiation, 0.5C delithiation

[0143] [Table 6]

[0144] The charge / discharge capacity characteristics were measured as shown in the graph in Figure 3, where the capacity at the end of charging is the charge capacity and the capacity at the beginning of discharging is the discharge capacity. The ICE is calculated by dividing the discharge capacity by the charge capacity. Referring to Table 6, it can be seen that the half coin cells prepared using Examples 1 and 2 and the half coin cell prepared using Comparative Example 1 exhibited almost equivalent performance in terms of the charge capacity, discharge capacity, and ICE measurements. Examples 1 and 2 used a porous carbon support stabilized without crushing solid pitch pellets in step (3), while Comparative Example 1 used a porous carbon support prepared by crushing solid pitch pellets using a conventional manufacturing method and then stabilizing the crushed solid pitch pellets. Considering the above, the method for manufacturing a porous carbon support according to the present invention can produce a porous carbon support with excellent pore characteristics without a separate crushing process for solid pitch pellets. As a result, the method for manufacturing a porous carbon support according to the present invention can significantly improve process efficiency.

[0145] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and the accompanying drawings, but should be limited by the appended claims. Therefore, various substitutions, modifications, and changes may be made by a person skilled in the art without departing from the technical spirit of the present invention as set forth in the claims, and these are also included in the scope of the present invention. [Industrial Applicability]

[0146] The present invention can provide a method for producing a porous carbon support, including: (1) a step of synthesizing pitch by pyrolysis and condensation polymerization of a petroleum-based raw material; (2) a step of solidifying and pelletizing the pitch to obtain solid pitch pellets; (3) a step of stabilizing the solid pitch pellets without crushing them; and (4) a step of carbonizing the stabilized pitch pellets to obtain a carbonized body.

Claims

1. (1) synthesizing pitch by pyrolysis and polycondensation of a petroleum-based raw material; (2) solidifying and pelletizing the pitch to obtain solid pitch pellets; (3) stabilizing the solid pitch pellets without crushing them; (4) carbonizing the stabilized pitch pellets to obtain a carbonized body.

2. 2. The method for producing a porous carbon support according to claim 1, wherein the polycondensation temperature of the pitch synthesis in step (1) is in the range of 350°C or more and / or 500°C or less.

3. 2. The method for producing a porous carbon support according to claim 1, wherein the softening point of the pitch synthesized in step (1) is 200° C. or higher.

4. The method for producing a porous carbon support according to claim 1, wherein the thickness of the solid pitch pellet in step (3) is 1 mm or more.

5. The step (3) includes heating the unground solid pitch pellets at a temperature of 250°C or more and / or 400°C or less, The method for producing a porous carbon support according to claim 1 , wherein the heating is performed by microwaves or plasma.

6. 2. The method for producing a porous carbon support according to claim 1, wherein the oxygen content of the stabilized pitch pellets in the step (3) is 10 wt % or more.

7. 2. The method for producing a porous carbon support according to claim 1, wherein the distribution deviation of oxygen content in the cross section of the stabilized pitch pellet in the step (3) is 30% or less.

8. The method for producing a porous carbon support according to claim 1, further comprising the step of depositing silicon after step (4).

9. The deposition may be carried out at a temperature of 300° C. or more and / or 600° C. or less and at a flow rate of 50 sccm or more and / or 500 sccm or less of silane (SiH ４ 9. The method for producing a porous carbon support according to claim 8, wherein the method is carried out under a gas atmosphere.

10. The method for producing a porous carbon support according to claim 8, wherein the content of the deposited silicon is 10 wt% or more based on the weight of the entire porous carbon support.

11. A porous carbon support produced by the production method according to any one of claims 1 to 10.

12. A battery negative electrode material comprising the porous carbon support of claim 11.

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